Antenna system



R. M. SPRAGUE ANTENNA SYSTEM Julie 26, 1945.

3 Sheets-Sheet 2 Filed June 15, 1943 K KT' 60f INVENTOR ATTORNEY June 26, 1945.

ANTENNA S YS TEM R. M. SPRAGUE 2,379,260 I Filed June 15, 1943 3 Sheets-Sheet 3 H M a l 2.4

/ x I T -j- ROBE-IP71. Jm maui INVENTOR ATTORNEY Patented June 26, 1945 of Delaware ANTENNA SYSTEM" Robert M. Sprague, Hicksville, N. Y. assignor to Press Wireless, Inc., Chicago,

111., a corporation Application June 15, 1943, Serial N 490,844

12 Claims.

This invention relates to antennae and more particularly to antennae of the type using long wires, or non-resonant antennae such as so-called rhombic antennae.

A principal object of the invention is to provide an antenna of the rhombic or diamond type having greater radiating and directional effectiveness.

v Heretofore, in Connection with so-called rhombic antennae used for radiation or transmission, as distinguished from reception, the far part of the rhombic has been required to dissipate energy which if not dissipated, would radiate in the backward direction thus curtailing the directional efiiciency of the antenna. This dissipation has been achieved heretofore in twoways. One method utilizes a relatively long twowire transmission lineoi iron wires having a high wave attenuation; the other method is to i'iermimate the far end of the rhombic in a lumped resistance equal to the wave resistance or the antena. Each of these known methods possesses disadvantages which it is .the purpose of this invention to overcome.

Accordingly, another principal object of the.

invention is to provide an improved dissipating termination for a directional antenna of the rhombi'c or diamond type.

A feature of the invention relates to a rhom'bic type antenna with a rhombic type dissipating line.

Another feature relates to a rhombic-type antenn'a with a dissipating line so designed that the ground area required to support the antenna and.

the dissipating line is not materiallygreater than that required for the antenna proper.

A further feature relates to a rhombieantenna with a specially designed and shaped dissipating line whereby no additional supportingpoles are required for the dissipating line beyond those.

required for the antenna proper.

Another feature relates to a rhombic antenna system having a dissipating line which is, special-v ly designed, shaped and supported with respect to the antenna proper, so that the surge 'im pedance is maintained constant along the entire system including the feeder lines.

A further feature relates to a double, rhombic antenna system, one section of which is a wave radiator and the other a wave dissipator, with the legs of each section diverging according to an exponential law whereby undesirable reflections along the antenna, resulting from a change in impedance at localized points, are eliminated.

A still further feature relates to a rh'ombie ntenna having the antenna or radiating section axes of the rhombus.

proper, formed of double wires with the wires at a slight angle to each other, both in a verticalplane" and-in a horizontal plane.

Other features and advantages not specifically enumerated will be apparent after a consider-.

ation of the following detailed descriptions and the appended-claims.

Inasmuch as the invention is concerned primarily with the physical arrangement of the antenrla wire system, only those parts of a radio system will be described as are necessary to an understanding or the invention. Furthermore,

the drawingsare intendedt'obe schematic only.

Accordingly, in the drawings,

Fig. 1 is a perspective view of an antenna syse t'em according'to the invention.

Figs. 2, 3 and' l are enlarged details to show one manner of separating and guiding the wires adjacent the pole supports.

Figs. 5 an'd61are modifications of Fig. 1.

Fig. 7 is" another modification of Fig. 1.

Figs; 8 and 9 represent respectively further modifications; and I Figs. '10 to 14 are various views of a still further modification.

Referiingto Fig. 1, the antennasystem as a whole consists of a radiating section I, and a dissipating section 2-, both: of which are of rh'ofiibic or diamond formation and are in superposed relation, preferably with the corresponding wires of the two sections in substantially the same vertical" "plane. As is well-known, the rhombio-type antenna :hasdesirable directional properties and consists fundamentally of fourlong wires arrangedin diamond or rhombic contour, with the" angular relations of the sides of the rhombus such that the major radiation of the radiation lobes of each wire are additive in phase when considered 'in the direction of the major This type of antenna is usually located at a considerable height above ground, e. 'g.-, feet and is formed of copper or' other low resistance wire suitably supported at the apices'of the rhombus on four wooden po'les'3, 4, .5 and It, suitably anchored at their l'owerends in the ground. The section 2 .is either of copper wire or preferably of stainless .steel wireor the like. i v

The apex portions of the antenna maybe .supported on any well-known type of .stando'fi insu l'ators and *antenna strain or .tensioning devices. The arrangementshownin Figssllto 4, using the supporting and spacing insulators l, 8,19 and i0, is merely illustrative and sc'hematic..

accordance with theinveritiomthedissipating section 2 which is similarly supported on the posts 3 to 6 by suitable insulators, is located as close to the ground as possible, its proximity to ground being limited only by safety considerations of personnel, vehicle clearance and the like. A convenient height above ground has been found to be 8 to 10 feet.

The numeral II represents any suitable form.

Likewise, the transmission sion line conductor 22 to the legs 23 and 24. The

common junction or apex 26 of section 2 may be grounded through a suitable resistance bank corresponding to the surge impedance of the antenna system. By this arrangement, the backward field is dissipated in the section 2. Attenuation of the currents flowing in the section 2 is effected not only by the ohmic resistance of the wires I'I, I8, 23, 24, but also by theapparent resistance resulting from its closeness to ground. In view of the latter factor, it is possible to make the rhombic of copper. wire.

Instead of making the two sections I and 2 of simple diamond or rhombic contour, the sections may be shaped so that the opening angle between legs I4 and 20, and between legs I 5' and 2|, in-- stead of being uniform is of progressively varying size looking away from the apex. Thus as shown schematically in Fig. 5, the wires may diverge from each other in such a way that the impedance is maintained constant for a critical distance considered along the major axis A. Thus in the case of an antenna having a major axis of 175 to 250 meters, this exponential divergence of the antenna wires of section I continues throughout the entire length, while those of section 2 diverge for a distance of approximately 40 or 50 feet from the apex. Likewise, the legs I5 and 2I should preferably converge so that the impedance approaching the apex 25 is constant. By this arrangement, it is possible to maintain a constant surge impedance from the apex 21 to the apex 26. It will be understood of course, that if desired, the transmission line I5, 22, may likewise have its conductors arranged to maintain the necessary constant impedance relations in the system.

Instead of relying on the variation of angular opening between the wires to maintain the surge impedance constant, each leg of the antenna may be formed of a pair of wires which diverge at a slight angle as will be described herein in connection with Figs. 10 to 14.

If desired, instead of grounding the apex 26 directly, the two legs I8 and 2| may be bridged by a resistance bank 28 (Fig. 6), which can be adiustably grounded. Resistance 28 should be of a value substantially equal to the characteristic or iterative impedance of the antenna systemat the frequency or frequencies at which it is intended to be operated. Preferably, the transmission line I 6, 22, is impedance-matched to the dissipating rhombic. Thus, undesirable wave reflection or standing waves are avoided throughout the entire length of the system from the apex 21 to the apex 26.

As shown in Fig. '7, instead of relying entirely on the dissipating rhombic 2, to dissipate the reverse fields, the dissipating rhombic may be connected to a two-wire iron conductor line 29, which may be connected to the apex 26. If desired. this apex 26 may be terminated in a second network of separated wires at a location where the desired ground-induced resistance is most favorable. The objections to this arrangement is that considerably greater ground area is required to accommodate the line 28, and the increased cost and inconvenience of the additional supporting poles required for this line.

Figs. 10 to 14 illustrate a modification wherein each leg of the rhombic antenna section, instead of being composed of a single wire, is composed of two wires which diverge from the apex at a slight angle. The plane of each set of wires is at an angle to the vertical instead of being directly superposed in the same vertical plane. Preferably, the dimensions A and B are proportioned with relation to the main antenna axes C and D in a predetermined ratio. Thus, in the case of an antenna whose major axis C is between 175 and 250 meters, and whose minor axis D i between 60 and meters, the dimension A may be between 1.2 to 2 meters, and the dimension B may be from 1.4 to 3 meters. In this case, the antenna section I consisting of the double-wire legs as above described, may have an average height of from 15 to 30 meters. The resistance R which terminate the rhombic should have a value which matches the characteristic or iterative impedance of the antenna. With the terminal resistance connected as shown in Figs. 10 and 11, the antenna functions as a uni-directional system which either transmits or receives in a direction along the major axis as represented by the arrows. With the terminal resistance disconnected from the antenna, it operates bi-directionally along the same major axis. It will be understood of course, that the antenna of Figs. 10 to 14, instead of being terminated directly at the apex by resistancejor dissipation purposes, may be provided with a downward extending transmission line similar to lines IB22 (Figs. 1 to 7), and this downward transmission line may be connected to a dissipating rhombic similar to rhombic 2 (Figs. 1 to 7)., which of course is supported on the same poles which support the plural wire rhombic antenna.

It will be understood of course, that while in the foregoing embodiments the wires of the rhombics are shown and described as being in substantially horizontal planes; these planes may be tilted to give any desired effect to the radiation. Thus, as shown in Fig. 8, the plane of the main rhombic I is horizontal or if desired it may be tilted so that the plane of the legs is at an anglejto the horizontal as is well-known in the rhombic-antenna art; whereas the plane of the dissipating section 2 may be inclined downwardly with respect to the horizontal. This downward inclination maybe either in a single plane or the plane of inclination may be curved downwardly as illustrated in Fig. 8. As shown in Fig. 9, the plane of the main rhombic I is curved upwardly while the plane of the rhombic 2 is curved downwardly.

Various changes and modifications may be made in the disclosed embodiments without departing from the spirit and scope of the invention.

What I claim is:

1. An antenna system comprising a radiating section and a dissipating section, each of said sections being in the form of a wire loop having major and minor axes and with the dissipating section mounted beneath the radiating section and connected thereto by a transmission line, the peripheries of said sections being in substantial vertical planar alignment.

2. An antenna system according to claim 1 in which the radiating section is supported at relatively great height above ground while the dissipating section is mounted relatively close to the ground to increase its dissipating powers.

3. An antenna system according to claim 1 in which both the radiating section and the dissipating section are of rhombic contour.

4. A rhombic-type antenna system comprising a main antenna section of rhombic contour and an auxiliary dissipating section also of rhombic contour with the legs of one section arranged in substantial vertical planar alignment with the corresponding legs of the other section so that the dissipating section reduces to a minimum the backward radiation from the main section.

5. A rhombic-type antenna system comprising an upper rhombic, a lower rhombic, and transmission line means connecting thelegs of the upper rhombic at the far apex with the legs of the lower rhombic at the far apex, and with the legs of the upper rhombic in substantial vertical planar alignment with the corresponding legs of the lower rhombic.

6. A rhombic antenna system comprising a main rhombic wire section, an auxiliary rhombic wire section, means to support said sections at their apices in superposed space relation and with the corresponding legs of the two rhombic sections in substantial vertical planar alignment, a two-wire transmission line connecting the far end of the main rhombic with the far end of the auxiliary rhombic the near endof the auxiliary rhombic being grounded.

7. A rhombic antenna system according to claim 6 in which corresponding superposed legs of the two rhombic sections are connected to a transducer in like phase.

8. A rhombic antenna system according to claim 6 in which the main rhombic section is connected to a two-wire transmission line, and the corresponding legs of the two rhombics are connected in series between one of the transmission line conductors and ground.

9. A rhombic antenna system comprising a main upper wire rhombic, an auxiliary lower wire rhombic, means to connect a radio transmitter or the like across two legs of the upper rhombic adjacent the near apex' thereof, means adjacent the far apex to connect the said ,two legs respectively to the legs of the auxiliary rhombic at its far apex, and means to ground the two legs of the auxiliary rhombic adjacent the near apex thereof, said rhombics being superposed in spaced relation so that the corresponding legs of the two rhombics are in substantial vertical planar alignment.

10. A wave radiating system comprising in sequence a rhombic-Wave radiator for radiation in a predetermined direction, a two-wire transmission line, a rhombic wave dissipator, the remote end of said dissipator being grounded, said dissipator being mounted in substantial vertical planar alignment with respect to said radiator so that back radiation from said radiator is substantially entirely dissipated.

11. A wave radiating system according to claim 10 in which said dissipating rhombic is grounded at its far apex through a resistance substantially equal to the characteristic impedance of the radiator.

12. A wave radiating system according tdclaim 4 in which the far apex of said auxiliary rhombic 40 is connected to a two-wire wave attenuation line.

ROBERT M. SPRAGUE. 

